Power unit for hydraulic presses



954 I w. ERNST 2,696,779

POWER UNIT FOR HYDRAULIC PRESSES Original Filed Sept. 15, 1949 3 Sheets-Sheet 1 mvsmon WALTER ERNST ATTORNEY T Q LL.

Dec. 14, 1954 W. ERNST POWER UNIT FOR HYDRAULIC PRESSES Original Filed Sept. 15, 1949 5 Sheets-Sheet 2 FIG- 3 I 54. 32 46 as 1 6 u 6 I [1 I06 f1! f' W k 44 24 m 38- 42 k HO 26 --J- 5 a: l8 i 1:

, 28 o f I H 30 a i 66 I o in 7 0 o 68 o a W a? a 36 V a )1 E L l J INVENTOR 14 WALTER ERNST l6 WM AT TORN EYS Dec. 14, 1954 w. ERNS T' 2,696,779

POWER UNIT FOR HYDRAULIC PRESSES Original Fi led Sept. 15, 1949 3 Sheets-Sheet 3 22 51 64 s 54 62 26 l 4 Y 24 i I i 1/? 52 ATTORNEYS provision of more apparent United States Patent wealth Engineering Company of Ohio, Dayton, Ohio, a corporation of Ohio .Original application September 15, 1949,, Serial No.

115,901, now Patent No. 2,672,836, dated March 23, 1954. Divided and this application December 21, 1950, Serial-No. 202,056

2 Claims. (Cl. 100-269) This application relates to hydraulic presses, and is a division of my copending application Serial No. 115,901, filed September 15, 1949, now Patent'No. 2,672,836.

One of the'primary objects of this invention is the provision of a press construction better adapted to modern technology than presses constructed according to the prior art, in that the press is easier to manufacture and to modify, and is relatively simple to service and repair.

Presses of the general type with which this invention is concerned are well-known in the art, but heretofore almost every press manufactured was especially designed for a particular job or for a particular class of work. This procedure not only involved expenditure of a great deal of designing time, but also, in most instances, re

quired the making of new patterns and the like for each job to be built.

The customary manner of building a hydraulic press utilizes a single large casting for both the'head and cylinder. Because of this, each press is adapted for operation ..at only one tonnage, and if the job requires less" than that tonnage, the press operates in a somewhat lnefiicient manner due to the factthat more fluid is pumped to and from the power cylinder than is necessary.

Since modern hydraulicpresses operate at'high pressures, it is of importance for the cylinder to be absolutely .nonporous to prevent oil leakage or seepage therefrom. 'The heads of presses are ordinarily cast, and because cast iron is often of a somewhat porous texture, it is necessary for the suppliers of press heads to .charge apremium price whenever the cylinder is integral with the head. The strength of a head casting of this nature is not materially diiferent between a slightly porous casting and a dense casting, and, accordingly, a head casting having aleaky cylinder is many times discarded when it would otherwise make a perfectly satisfactory work member.

The particular object of the present invention 'is the a headand cylinder arrangement for a hydraulic press which overcomes the difficulties referred to above. forming themain head casting and the cylindercastmg separately and assembling them in the press to form a complete unit.

The removability of the press cylinder according to this invention requires-that it be disconnected from the hydraulic conduits through which fluid is conducted to and from the cylinder when the press operates.

A still further object is the provision of a novel arrangement whereby the removable cylinder in an arrangement according to this invention can readily be connected to or disconnected from the supply conduits'leading thereto. 7

These and other objects and advantages will become upon'reference to thefollowing description taken in connection with the-accompanying drawings'in which:

Figure 1 is a partial front elevation showing the upper end of a press constructed according to my 111- vention;

Figure 2 is a side view thereof looking in from the right side of -Figure 1;

Figure .3 is a vertical sectional view indicated by line 33' on Figure 2;

Figure 4 is anenlarged fragmentary view showing 'the valving 'arrangement'associated with the push-back .side of thepress ramand cylinder;

This particular object is accomplished by Patented Dec. 14, 1954 bed, and uprights in rigid alignment by means of the enlarged-diameter portions 18 which fit into machined bores where the head and uprights meet and also where the uprights and bed meet.

Suitable nuts, as at 20, are threaded onto the ends of the strain rods for holding the head and bed in rigid assembled relationship with said uprights.

According to this invention, the press head and cylinder mounted therein are separate-castings. This is a preferred practice because the cylinder can be of the exact size required to do the work which is to be placed in the press, and in this manner full advantage can be taken of the available hydraulic horsepower. Also, the cylinder castings are easier to produce, as the combination of thick and thin sections is avoided. The amount of scrap, should it become necessary to throw away a casting due to leaks therein, is greatly reduced, and this afl'ords a desirable economy.

Reference to Figure 3 will indicate the manner in which the cylinder and head are combined according to this invention. The press head has a central bore 22 therein having smoothly machined parts at its upper and lower ends, as at 24, which receive corresponding machined parts on the cylinder casting 26. Cylinder casting 26 preferably is flanged, as at 28, below the press head, and bolts 30 may extend through this flange into the press head for retaining the cylinder and head in assembled relationship.

It will be noted that flange 28 sustains the vertical thrust on the press :cylinder.

At its upper end the press cylinder is preferably engaged by a ring 32 mounted on the press head and packing, not shown, may be compressed between said ring, head, and cylinder to provide a firm and fluid-tight sup .port for the upper end of the press cylinder.

The cylinder is axially bored for receiving the double acting plunger 34 that extends out the bottom of the cylinder for connection with press platen 36, as by means of the split ring 37.

Plunger 34 may also be axially bored from its upper end, as at 38, for receiving the auxiliary ram 40 that is preferably hollow, as at 42, to permit fluid to be .supplied to the lower end of bore 38.

Fluid is adapted for being supplied to the upper end of the press cylinder by a conduit 44 that communicates witha passage46 in the upper endof the press cylinder. This arrangement will be seen in Figures 3 and 6.

In the arrangement shown, passage 46 communicates withthe hollow interior 42 of auxiliary plunger 40 and also communicates with inlet 48 of a pressure shift-over valve 50 which is preferably mounted on the side of the upper end of cylinder 26.

The press head is provided with a plurality of spaced bores 52 on which are mounted surge valves 54. One of these valves is illustrated in some detail in Figure 5, and it will benoted that it comprises the valve plunger 56 which is normally urged by spring 58 to interrupt pressure suppliedthereto through the conduit means 62 when the press plunger is moving upwardly. As will be seen in Figures 3 and 6, there is one surge valve associated with the auxiliary plunger 40, while there are two surgevalves associated with the cylinder 26.

, Fluid connection is had with thelower side of plunger 34 by conduit .64 which communicates with a passage 66 formed in flange 28 at the lower end of cylinder 26. A resilient annular sealing ring 90 (Fig. 3) or 90 (Fig. 4) is seated in an annular groove (not numbered) in an abutting face of either the head 12 or flange 28.

The arrangement of this passage and the valves associated therewith will be seen in Figure 4. Passage 66 communicates with the upper face of a check valve member 68 which is spring biased toward its closed position, but which will yield in response to a relatively small pressure from passage 66 to admit fluid from the said passage through port '70 into the lower end of cylinder 26. Check valve 68, however, prevents the escape of fluid from the lower end of the cylinder into passage 66.

Fluid leaving cylinder 26 must pass through conduit 72 which opens into a relief valve 74 beneath the balanced piston 76 thereof. Piston 76 of the relief valve will move upwardly to communicate conduit 72 with conduit 78 leading to passage 66 whenever pressure standing on the opposite faces of piston 76 reaches that value which will cause auxiliary relief valve 80 to open and to exhaust fluid from above piston 76.

In a like manner, valve '76 can be opened by shifting movement of a valve 82 which will be described hereinafter, and which is employed for the purpose of bringing about the free exhausting of the lower end of cylinder 26 when so desired. The valve 82 is normally urged closed by a spring 84- and is adapted for being opened by energization of solenoid S1, which, in turn, is adapted for being energized when a limit switch LS1 is closed by a cam 86 carried on the press platen 36. As will be seen in Figure 4, LS1 is connected in series with S1 between the power lines L1 and L2.

It may be noted at this time that the conduits 44 and 64 are permanently aflixed in the press head as by welding, so that the removing of the press cylinder or the placing of it in the press is a relatively simple matter and involves a minimum of pipe connections. For example, at the upper end of the cylinder a small elbow fitting 88 may be employed for making connection be tween conduit 44 and the press cylinder, while at the lower end of the press cylinder the O-ring 90 provides the means for effecting connection between conduit 64 and passage 66.

The press platen is preferably guided on the press uprights, as will be seen in Figures 1 and 3, by gib members secured to the platen and bearing on smoothly machined rails or guide surfaces carried by the said uprights.

Turning now to the hydraulic power unit for the press and to the arrangement thereof, including the pumps, tanks, reservoir, and other auxiliaries, these are mounted on the head of the press, and the arrangement thereof will best be seen on reference to Figures 1, 2, and 3.

Mounted on the upper surface of the head of the press is the reservoir 60 comprising any suitable constructional arrangement for retaining the hydraulic fluid for the press and for supporting the press drive motor 100. Into this reservoir 60 extends the upper end of the press cylinder 26 and the previously described surge valves 54 and the passages 52 which they control provide a means for communicating with reservoir 60 and with the interior of cylinder 26.

At this time it will be noted that the packing means which is compressed by gland 32 around the top of cylinder 26 is useful for sealing against leakage of hydraulic fluid from reservoir 60. The upper surface of reservoir 60 mounts drive motor 100 and belted thereto is the main pump 102.

The main hydraulic pump 102 for supplying pressure fluid to the opposite sides of press ram 34 is mounted on the tank arrangement 104 that is carried on the back of the head 12 of the press. Pump 102 is belt-connected to drive motor 100, and this is of advantage in enabling motors of standard speed to be utilized with the customary pumps which generally operate at considerably lower speed than standard speed motors.

The belt-connecting of the drive motor to the pump is also of distinct advantage in supplying the foreign market and other areas where odd frequencies of current supply make it difficult to drive the pump at the proper speed by directly connecting it to the drive motor.

The pump 102 is of the conventional reversing type, preferably having controls integral therewith, and has its two discharge ports connected by conduits 106 and 108 with the flanges 110 and 112 mounted on the side of the press head, as will be seen in Figures 2 and 3.

The arrangement illustrated is of great advantage, because the pump and its conduits can readily be removed from the press at any time for repair or replacement, and the connections between the flanges 110 and 112 and the press cylinder and the other auxiliaries of the press need not be disturbed.

Pump 102 rests on the top wall of tank 104 and is connected for drawing any make-up fluid required from the said tank by means of any suitable and conventional shuttle valve arrangement, not illustrated.

Operation A number of the features of this invention may be better understood by considering the operation of the press. First considering the operation of the press on a single action cycle, let it be assumed that the press ram is in its uppermost position and that the motor 100 is energized thereby driving main pump 102. Pump 102 is normally centered by controls integral therewith, and the main platen therefore remains in its uppermost position. An advancing stroke of the main ram and platen of the press can be had by causing pump 102 to shift into position to draw fluid in through conduit 108 leading to the push-back side of the said ram and to discharge fluid through the conduit 106 leading to the upper end of the ram.

During the initial advancing movement of the press platen, valve 82 is so positioned as freely to drain fluid from above piston 76 in valve 74, thereby permitting valve piston 76 to raise and to connect conduit 72 with passage 66 leading to conduit 108. it will be evident that the press ram will move downwardly as rapidly as the pump draws fluid through conduit 103. During this initial advancing movement of the press ram, the surge valves 54 open to admit fluid from tank 60 to the top surface of the press ram.

When the platen has advanced to a predetermined point, cam 86 actuates limit switch LS1, thereby de-energizing solenoid S1 which permits valve 82 to close, thereby interrupting the exhaust of fluid from above valve piston 76. This causes valve 74 to close, thus entrapping fluid in the push-back side of the press ram.

The pump 102 will now deliver fluid under pressure through conduit 62, Fig. 5, and passage 46 through hollow ram to act on that part of the upper surface of the press ram directly beneath ram 40. The press ram and platen will now advance at a rate determined by the rate of fluid supply from pump 102 through conduit 106.

The fluid expelled from the push back side of the ram will be discharged through valve 74 when the pressure on the side fluid reaches that value which will cause opening of auxiliary relief valve 80.

If the pressure requirements of the job being done are suflicient, then pressure shift-over valve will open and connect passage 46 with the upper surface of the press ram. The rate of advance of the press ram and platen is now determined by the rate of fluid supply through conduit 106 to the entire upper face of the said press ram.

Retracting movement of the press ram can be had merely by reversing the direction of delivery of pump 102. The pump when reversed delivers fluid through conduit 108 to the push-back side of the press ram. During retraction of the press ram pressure fluid is conducted through pilot conduit 62 to the several surge valves 54 and causes them to open, thereby permitting free discharge of the fluid from the upper Working areas of the press ram back into tank 60.

Upward movement of the press ram and platen is accomplished by fluid supplied to the push back area of the ram from channel 66 through check valve 68 and port 70. It will be noted that check valve 68 offers substantially no resistance to this fluid flow.

It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions, and, accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

I claim:

1. In a hydraulic press, a frame, a hollow head horizontally supported upon said frame, said head having a vertical bore therethrough, there being a flat face on the lower surface of said head and surrounding said bore, a cylinder positioned in said bore for receiving an actuating ram for a platen of the press, upper and lower portions of said cylinder extending beyond the upper and lower surfaces respectively of said hollow head, a radial flange on the lower portion of said cylinder, there being a flat face on the upper surface of said flange, detachable means securing said flange against said head whereby said flat faces are in abutting relationship, iirst and second tubular conduits fixedly mounted in said hollow head and forming an integral part thereof to supply fluid to said cylinder, there being first passage means extending vertically through the upper surface of said head adjacent said bore, one end of said first conduit secured within said first passage means, means connecting said first passage means with the upper end of said cylinder, there being second passage means through the flat face of the lower surface of said hollow head adjacent said bore, and there being third passage means extending vertically into said flange and opening to the interior of said cylinder at the lower end thereof, said third passage means being adapted for registration with said second passage means, one end of said second conduit means being secured in said second passage means, each of said conduits extending to a side surface of said hollow head and being fixedly received therein for connection with other conduits.

2. In a hydraulic press, a frame, a hollow head horizontally supported upon said frame, said head having a vertical bore therethrough, there being a flat face on the lower surface of said head and surrounding said bore, a cylinder positioned in said bore for receiving an actuating ram for a platen of the press, upper and lower portions of said cylinder extending beyond the upper and lower surfaces respectively of said hollow head, a radial flange on the lower portion of said cylinder, there being a flat face on the upper surface of said flange, detachable means securing said flange against said head whereby said flat faces are in abutting relationship, first and second tubular conduits fixedly mounted in said hollow head and forming an integral part thereof to supply fluid to said cylinder, there being first passage means extending vertically through the upper surface of said head adjacent said bore, one end of said first conduit secured within said first passage means, means connecting said first passage means with the upper end of said cylinder, there being second passage means through the flat face of the lower surface of said hollow head adjacent said bore, and there being third passage means extending vertically into said flange and opening to the interior of said cylinder at the lower end thereof, said third passage means being adapted for registration with said second passage means, one end of said second conduit means being secured in said second passage means, each of said conduits extending to a side surface of said hollow head and being fixedly received therein for connection with other conduits, there being an annular groove in the flat face in at least one of said flange and head, said groove encircling said second passage means, and a resilient annular sealing member within said groove to form a fluid-tight seal when said flange and said head are brought into abutting relationship.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 674,647 Drennan May 21, 1901 812,228 Von Philp Feb. 13, 1906 2,003,922 Claret June 4, 1935 2,283,168 Ernst et al May 19, 1942 2,357,507 Ernst Sept. 5, 1944 2,384,161 Ernst Sept. 4, 1945 2,484,908 Purcell Oct. 18, 1949 2,512,531 Renkenberger June 20, 1950 2,516,301 Denison July 25, 1950 2,544,731 Sedgwick Mar. 13, 1951 FOREIGN PATENTS Number Country Date 229,681 Switzerland Feb. 1, 1944 

